Effect of inoculants and fibrolytic enzymes on the fermentation characteristics, in vitro digestibility and aflatoxins accumulation of whole‐crop corn silage

Abstract

Two additives (bacterial inoculants and fibrolytic enzymes) were tested for their effects on fermentation characteristics, in vitro digestibility, mold counts and aflatoxin (B1, B2, G1 and G2) content in corn silages. Whole‐plant corn was harvested with one‐half milk line stage and ensiled after the following treatments: (i) untreated (CON); (ii) bacterial inoculants at 105 CFU g−1 of fresh forage (B); (iii) fibrolytic enzymes at 100 U g−1 of fresh forage (E); and (iv) mixture of bacterial inoculants and enzymes at 105 CFU g−1 and 100 U g−1 of fresh forage, respectively (B+E). All the additives increased the lactic acid content and in vitro dry matter digestibility (P < 0.05), decreased ammonia nitrogen content (P < 0.05). E and B+E decreased the neutral detergent fiber content and increased the crude protein, in vitro digestibility of neutral detergent fiber and crude protein (P < 0.05). Aflatoxins content and mold counts for treated silage were lower than untreated silage (P < 0.05) throughout the air exposure stages (0, 1, 5, and 10 days). Additionally, the aflatoxins were not detected in B treated silage after 0 day exposure to air and in B+E throughout the air exposure stages.

Effects of xylanase on the fermentation profile and chemical composition of sugarcane silage

“…During aerobic exposure, acids and other substrates are oxidized by aerobic bacteria, yeasts and moulds (McDonald et al, 1991). Ying et al (2017) reported increased aerobic stability in maize silage treated with fibrolytic enzyme and associated the increase in acetic acid concentration with improvements in aerobic stability. Danner et al (2003) reported that the existence of acetic acid was able to inhibit the growth of yeasts and moulds to improve aerobic stability.…”

“…Gandra et al (2017) reported positive effects of xylanase (XYL) and cellulase addition on fibre digestibility when animals were fed with sugarcane silage, whereas no effect of these enzymes was observed in animals fed a maize silage diet. On the other hand, the addition of enzymes in grass (Mandebvu et al, 1999;Dean et al, 2005), sorghum (Xing et al, 2009) and maize (Sheperd and Kung, 1996;Ying et al, 2017) at ensiling increases silage digestibility. Degradation of xylan produces mainly acetic acid as an end-product during fermentation (Fred et al, 1919;Dehghani et al, 2012).…”

Exogenous fibrolytic enzymes affect the nutritive value and the performance of Nellore bulls when added to corn-based silages

“…The authors claimed that the easily digestible components of the fiber fraction are more susceptible to be hydrolyzed during the silage fermentation. However, the increase in NDF digestibility at 90 days, for the doses of E150 and E200, are more similar to the results of Sheperd and Kung (1996) and Ying et al (2017), even though no differences for NDF content were found to these two treatments at the referred time of storage. Digestibility in vitro studies have shown that the use of EFE, as a ruminal feed additive, is effective to increase the DM or NDF digestibility , but the optimal ratio between endoglucanase and xylanase to improve the digestibility should be more than 0.4:1 ).…”

“…Regarding the NDF content and digestibility, the effects were not clear, since only the highest dose (200 g/ton of DM) reduced both at 60 days of storage. However, the majority of studies where EFE was applied to corn silages at ensiling, are in concordance about the reduction of the NDF content (Spoelstra et al, 1992;Higginbotham et al, 1994;Sheperd and Kung, 1996, Colombatto et al, 2004Ying et al 2017). The studies previously mentioned attributed the NDF content reduction to the degradation of the cell wall carbohydrates of the corn silage.…”

“…The decrease in the DM content, as the dose was augmented, was accompanied by a numerical increase of the DM losses. Spoelstra et al (1992), Sheperd and Kung (1996), and Ying et al 2017, also showed a decrease of the DM content in corn silages treated with EFE. These losses might be attributed to the formation of acetic acid, as will be discussed later.…”